Induction machine



May 10 g 1927. 1,628,454

M, HOBART INDUCTION MACHINE Filed. Aug. 24, 1925 2 Shwts-Shmfi l L: JGE

Irv/armor":

Henr- M. HObHTt: b3 fl M H i S ALLOTHEH- LGZSAM ay 0 H. M. HOBART INDUCTION MACHINE Filed Aug. 24, 1925 2 Sheetwshewt :r n 1.}? 0 0 M m em A v8 m .nrfiH w Pateme Me 10, 19270 ewes STATES PATENT HENRY HIQBART, 0F SCHENECIADY, NEW YORK. ASSIG-NOR GENERAL EI-EUTRIQ COMPANY, A. CGREGRATION OF NEW' YORK.

INDUCETON mscmmz.

App-licatiam mac? hag-mt 24, 1923. Serial 6592531.

My invention relates t0 induction machmes and m pertlcular m s spews? eescedie eonneetisn inducfie'n meter The inventwn 1s parshculm'ly edvsn' geeus fer a high vei''ege, Lew speeei instsH-L en ferifis nyineipz a'i ehlee'i; the eiiminer m 4 s an Immense meters COHIOBQWQ TI iieve is be Revel 2m painted out the eieie Fm betsey unde'x'smmdin e v :ve'ferenee is nae ole t0 "the "ieflewing Men mken in esr lnectio n with the sees, TH pmying (Evenings in which 1 represents the sub-weld appe ee sf sneuenv bedimen; my inventien snewing connected advance! fee imp? power fseier and; increasing the stalling; of :1 special essez Lde connected imemetien chine; dis-grammatically the winding wrsngement 055 two iudue meters cenneeteci in a e e wit Fines the having; a pale Feed hers; and Yeprese s the z'eimiv" News pmddce "we 'vewjs 35 by awn thereix'zh Ref-err the imwimggs and name Hemimly 1 snca :13, a'epresenw m primary finding e f fire peily ihe- (maiden mscnime shown me v 17E; in 1 Fee the purpose i. enci because 2. very sine} wenid be empisyefl in e frail nxessme the be Qeseribed Y 93'? repxesemis iiuetmn machine r is s rater Wind-ii g, 28

winding; 2? 3, Pete .Ldings may be eithev cage bar iiy'gen Winding; opemiii v imp;

will e2" see i pose 0f e ""zetien and bees e 01 sdvmhi's 1 securing they v 5 5 eens idere as v I windings have sham Qi'ffihm respectively, 011 their m while he inney ends which ewe? are interemm'eeted by a series of lziii'lfil'iGl'lt eennee'mens represented cu: "mm rotor Wmcbngs W111i. be

01 A. Wound iahe usual type of sieted cures both mounted on. the {ES/111%, shszzi zi; the

\ "bars of wmdm'g 28 numbered Sisor Winding n n connect-ct to the h e by means 05 01 1mg 21 1s as the shaming vesxstu sent-sci 33 er t0 the g: meails 0i switch 41.

The manner 01? mteyceymeetrwg bar rotors 1s represented tively from 1 0 24 ii bars 0? 9 9 with which the u connected are numberel eceezfiingiy, this system of connec cis;

in the left hams? m t'n ough the currents windings, 8-p01e in the eppesite diree'bien, machine. This mist? cm'danee with the stats izien; Elem e137 that the 0 e3 5 ihe magnetie flux in the seeo esge system sh all be seposise to the dime 0'5 mechanics remtie The two fluxes ens u, shout by his connectie wesened in Fig. 3 represents the bi peiar machine safl rzhe levee? Spoie flux 0f the 8-1 the b ying une lnstsnt are represeneee ms hese 1y 1g; under n er the pi 'POS6 of nmfe c he remtien, The bar spec eve of 3- is number 3212? nmnbering 01": Fig, 53., 8-p0le flux curve the 8-peie b 1n she Ewe eom'espending the siip; Whieh dusing no?- crl hers for the sake ofsimplicity.

.- thereby secured improves the etliciency.

In this explanation I have selected a relatively small number of slots and pole num- However, it will be evident that various other combi- 1 nations may be carried out without departfrom a high voltage source.

ing from the sphere of my invention. The decision as to. whether the rotor windings should be coil or bar windings will sometimes depend upon the pole and slot numbers selected in any given case. The winding which requires the least complicated interconnection and the least copper in the interconnection should be selected when such considerations are of enough importance to offset the advantage of the features of ruggedness and absence of slot insulation and higher etiiciency which characterize the squirrel case construction.

In the example given, the machine will be started by closing switch 37 with switch 41 open and all the resistance 38 in the circuit of the secondary stator winding 27. The resistance 38 will then be gradually short circnited and when the machine is up to speed, contacts 39 will be opened and switch 4] closed to connect the cascade to the phase advancer 40. The machine described will run at the speed of a lO-pole induction motor, the bi-polar machine comprising windings 26 and 28 acting largely as a transformer.

My invention is believed to be especially beneficial where there is limited space and where a low speed motor is required to run A primary transformer will ordinarily not be required, since the first member of the cascade system when designed with very few poles as compared with the secondmember. constitutes practically a step-down transformer with its high voltage winding on the stator. The absence of slip rings and bru"hes removes a. source of deterioration inevitable with the usual type of high starting torque induction vancing auxiliaries. The rating out an ordinary stow speed induction motor, as well as an ordinary cascade set, is usually limited by the stalling load. The present construction removes this limitation since it permits of increasing the stalling load by employing a phase advancer without introducing the ob ectionable feature of slip rings In accordance with the provisions of the patent statutes. I have described the princi les of operation of my invention together with the apparatus which I now consider to possess the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States, is 1- 1. An induction cascade comprising a pair of induction machines of different pole num-. bers having cooperating coil wound stator and bar wound rotorwindings, the rotor windings being mounted adjacent each other on the same shaft and interconnected in cascade relation by a system of continuous conductors. i

2;" An indw tion cascade comprising a pair of induction machines having different pole numbers and having cooperating stator and rotor windings, the rotor windings being mounted on the same shaft and comprising bars short circuited on one end and having their other ends directly interconnected in cascade relation.

3. A cascade connection comprising'a pair of induction machines having. stators woun d for different pole numbers and cooperating rotors mounted on the same shaft, the rotors com rising slotted cores having the same num er of slots, single conductors in each of said slots, said cond ctors'b'eing short circuited onvone end of their respective cores, the free end of each conductor being directly connected to a free end of a conductor in the other rotor in such relation as to reverse the phase rotations therebetween and to change the polenumber to correspond with the pole numbers of the stator.

i. In an induction motor cascade a bar wound secondary member for a first machine of the cascade and a bar wound primary member for a second machine of thecas'aidc, said members having their windings short circuited on one end only, the other ends being directly interconnected in reversed phase rotation and for different pole numbers. motors and induction motors with phase ad- In witness whereof. I have hereunto set myhand this 23rd dav of August. 1923.

HENRY M. HDBART. 

